This invention relates to pharmaceutical compositions containing combinations of estrogen agonists/antagonists and statins, and pharmaceutically acceptable salts thereof, kits containing such combinations and methods of using such combinations to prevent bone loss and/or promote bone formation and to lower blood lipid levels. The compositions and methods are useful for treating subjects suffering from osteoporosis, bone fracture or deficiency, primary or secondary hyparathyroidism, periodontal disease, metastatic bone disease, osteolytic bone disease, or undergoing orthopedic or oral surgery and treating cardiovascular disease, atherosclerosis and hyperlipidemia, or presenting with symptoms of cardiac risk.
Estrogen alters serum lipid concentrations, coagulation and fibrinolytic systems, antioxidant systems, and the production of other vasoactive molecules, such as nitric oxide and prostaglandins, all of which can influence the development of vascular disease.
The effects of estrogen therapy on serum lipid concentrations may result largely from estrogen-receptor-mediated effects on the hepatic expression of apoprotein genes. Many studies, including one large, randomized, controlled trial (The Writing Group for the PEPI Trial, JAMA 1995;273:199-208. [Erratum, JAMA 1995;274:1676.]) have documented that estrogen therapy in post-menopausal women decreases serum total cholesterol and low density lipoprotein (LDL) cholesterol concentrations, increases serum high-density lipoprotein (HDL) cholesterol and triglyceride concentrations, and decreases serum Lp(a) lipoprotein concentrations. Hepatic expression of the genes for several coagulation and fibrinolytic proteins is also regulated by estrogen through estrogen receptors.
Statins inhibit the enzyme HMG-CoA reductase that catalyzes the conversion of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) to mevalonate in an early and rate-limiting step in the cholesterol biosynthetic pathway. It is believed that this effect is responsible for statins being considered as potent lipid lowering agents. The bone-forming effect of statins may be due to their ability to increase bone formation rate possibly through the stimulation of growth factors such as bone morphogenic protein-2 (BMP-2) (Mundy, G., et al., Science, 1999;286:1946-1949).
Statins include such compounds as simvastatin, disclosed in U.S. Pat. No. 4,444,784; pravastatin, disclosed in U.S. Pat. No. 4,346,227; cerivastatin, disclosed in U.S. Pat. No. 5,502,199; mevastatin, disclosed in U.S. Pat. No. 3,983,140; velostatin, disclosed in U.S. Pat. Nos. 4,448,784 and 4,450,171; fluvastatin, disclosed in U.S. Pat. No. 4,739,073; compactin, disclosed in U.S. Pat. No. 4,804,770; lovastatin, disclosed in U.S. Pat. No. 4,231,938; dalvastatin, disclosed in European Patent Application Publication No. 738510 A2; fluindostatin, disclosed in European Patent Application Publication No. 363934 A1; atorvastatin, disclosed in U.S. Pat. No. 4,681,893; atorvastatin calcium, disclosed in U.S. Pat. No. 5,273,995; dihydrocompactin, disclosed in U.S. Pat. No. 4,450,171; ZD-4522, disclosed in U.S. Pat. No. 5,260,440; bervastatin, disclosed in U.S. Pat. No. 5,082,859; and NK-104, disclosed in U.S. Pat. No. 5,102,888.
High levels of blood cholesterol and blood lipids are conditions involved in the onset of atherosclerosis. It is well known that inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoA reductase) are effective in lowering the level of blood plasma cholesterol, especially low density lipoprotein cholesterol (LDL-C), in man (Brown and Goldstein, N Engl J Med, 1981;305:515-517). It has now been established that lowering LDL-C levels affords protection from coronary heart disease (see, e.g., The Scandinavian Simvastatin Survival Study Group: Randomised trial of cholesterol lowering in 4444 patients with coronary heart disease: the Scandinavian Simvastatin Survival Study (4S), Lancet, 1994;344:1383-89; and Shepherd, J. et al., Prevention of coronary heart disease with pravastatin in men with hypercholesterolemia, N Engl J Med, 1995;333:1301-07).
Coronary heart disease is a multifactorial disease in which the incidence and severity are affected by the lipid profile, the presence of diabetes and the sex of the subject. Incidence is also affected by smoking and left ventricular hypertrophy, which is secondary to hypertension. To meaningfully reduce the risk of coronary heart disease, it is important to manage the entire risk spectrum. For example, hypertension intervention trials have failed to demonstrate full normalization in cardiovascular mortality due to coronary heart disease. Treatment with cholesterol synthesis inhibitors in patients with and without coronary artery disease reduces the incidence of cardiovascular morbidity and the risk of mortality.
The incidence of cardiovascular disease differs significantly between men and women, in part because of differences in risk factors and hormones (Barrett-Connor E. Circulation 1997;95:252-64). The incidence of atherosclerotic diseases is low in premenopausal women, rises in post-menopausal women, and is reduced to premenopausal levels in post-menopausal women who receive estrogen therapy. (Barrett-Connor E., Circulation 1997;95:252-64; Stampfer M. J., et al., N Enql J Med 1991;325:756-62.; Grady D., et al., Ann Intern Med 1992;117:1016-37) Until recently, the atheroprotective effects of estrogen were attributed principally to the hormone""s effects on serum lipid concentrations. However, estrogen-induced alterations in serum lipids account for only approximately one third of the observed clinical benefits of estrogen (Grady D., et al., Ann Intern Med 1992;117:1016-37; Mendelsohn M. E., Karas R. H. Curr Opin Cardiol 1994;9:619-26; Bush T. L., et al., Circulation 1987;75:1102-9). The results, however, can be nonetheless significant. It is now also believed that the direct actions of estrogen on blood vessels contribute substantially to the cardiovascular protective effects of estrogen (Mendelsohn M. E., Curr Opin Cardiol 1994;9:619-26; Farhat M. Y. et al., FASEB J 1996;10:615-24).
The hormone estrogen has a profound effect in the vascular system of both men and women although its administration is associated with other effects that can be undesirable. Estrogen increases vasodilatation and inhibits the response of blood vessels to injury and the development of atherosclerosis. Estrogen-induced vasodilatation occurs 5 to 20 minutes after estrogen has been administered and is not dependent on changes in gene expression; this action of estrogen is sometimes referred to as xe2x80x9cnongenomic.xe2x80x9d The estrogen-induced inhibition of the response to vascular injury and the preventive effect of estrogen against atherosclerosis occur over a period of hours or days after estrogen treatment and are dependent on changes in gene expression in the vascular tissues; these actions are sometimes referred to as xe2x80x9cgenomic.xe2x80x9d
There are two estrogen receptors, estrogen receptor xcex1 and estrogen receptor xcex2, both of which are members of the superfamily of steroid hormone receptors. (Walter P., et al., Proc Nad Acad Sci USA 1985;82:7889-93; Kuiper G. G. J. M., et al; Proc Nad Acad Sci USA 1996;93:5925-30) Estrogen receptors xcex1 and xcex2 have considerable homology and, like all steroid hormone receptors, are transcription factors that alter gene expression when they are activated. (Walter P., et al. Proc Nad Acad Sci USA 1985;82:7889-93; Kuiper G. G. J. M., et al.; Proc Nad Acad Sci USA 1996;93:5925-30; Shibata H., et al. Recent Prog Horm Res 1997;52:141-65; Evans R. M., Science 1988;240:889-95; Brown M., Hematol Oncol Clin North Am 1994;8:101-12). Blood vessels are complex structures, with walls containing smooth-muscle cells and an endothelial cell lining. Vascular endothelial and smooth muscle cells bind estrogen with high affinity (Mendelsohn M. E., et al., Curr Opin Cardiol 1994;9:619-26; Farhat M. Y., et al., FASEB J 1996;10:615-24) and estrogen receptor xcex1 has been identified in both types of vascular cells in women and men, (Karas R. H., et al., Circulation 1994;89:1943-50; Losordo D. W., et al., Circulation 1994;89:1501-10; Venkov C. D., et al., Circulation 1996;94:727-33; Kim-Schulze S., et al., Circulation 1996;94:1402-7; Caulin-Glaser T., et al., J Clin Invest 1996;98:36-42) as well as in myocardial cells (Grohe C., et al., FEBS Lett 1997;416:107-12).
Estrogen receptor a activates specific target genes in vascular smooth-muscle and endothelial cells (Karas R. H., et al., Circulation 1994;89:1943-50, Venkov C. D., et al., Circulation 1996;94:727-33; Kim-Schulze S., et al., Circulation 1996;94:1402-7; Caulin-Glaser T., et al., J Clin Invest 1996;98:36-42; Koike H., et al., J Vasc Surg 1996;23:477-82). Estrogen receptor xcex2 is structurally and functionally distinct from estrogen receptor xcex1. Functional estrogen receptor xcex2 is also present in myocardial cells, in which it regulates the expression of nitric oxide synthases.
Bone is a tissue that is subject to turnover. The osteoblasts that produce new bone and the osteoclasts that destroy bone balance bone homeostasis. The activities of these cells are regulated by a large number of cytokines and growth factors, many of which have now been identified and cloned. Mundy has described the current knowledge related to these factors (Mundy, G. R., Clin Orthop 1996;324:24-28; Mundy, G. R., J Bone Miner Res 1993;8:S505-10.
Growth factors that stimulate bone formation have been identified. Among these latter factors are transforming growth factor, the heparin-binding growth factors (acidic and basic fibroblast growth factor), the insulin-like growth factors (insulin-like growth factor I and insulin-like growth factor II), and a recently described family of proteins called bone morphogenetic proteins (BMPs). All of these growth factors have effects on other types of cells, as well as on bone cells. The BMPs are novel factors in the extended transforming growth factors xcex2 superfamily. The BMPs were identified by Wozney J., et al. Science 1988;242: 1528-34, following earlier descriptions characterizing the biological activity in extracts of demineralized bone (Urist M., Science 1965;150: 893-99). Recombinant BMP2 and BMP4 can induce new bone formation when they are injected locally into the subcutaneous tissues of rats (Wozney J., Molec Reprod Dev 1992;32:160-67). These factors are expressed by normal osteoblasts as they differentiate, and have been shown to stimulate osteoblast differentiation and bone nodule formation in vitro as well as bone formation in vivo (Harris S., et al. J. Bone Miner Res 1994;9:855-63).
As osteoblasts differentiate from precursors to mature bone-forming cells, they express and secrete a number of enzymes and structural proteins of the bone matrix, including Type-1 collagen, osteocalcin, osteopontin and alkaline phosphatase (Stein G., et al. Curr Opin Cell Biol 1990;2:1018-27; Harris S., et al. (1994), supra). They also synthesize a number of growth regulatory peptides, which are stored in the bone matrix, and are presumably responsible for normal bone formation. These growth regulatory peptides include the BMPs (Harris S., et al. (1994), supra). In studies of primary cultures of fetal rat calvarial osteoblasts, BMPs 1, 2, 3, 4, and 6 are expressed by cultured cells prior to the formation of mineralized bone nodules (Harris S., et al. (1994), supra). Like alkaline phosphatase, osteocalcin and osteopontin, the BMPs are expressed by cultured osteoblasts as they proliferate and differentiate.
In premenopausal women, 17xcex2-estradiol produced by the ovaries is the chief circulating estrogen. Serum estradiol concentrations are low in preadolescent girls and increase at menarche. In women, they range from about 100 pg per milliliter (367 pmol per liter) in the follicular phase to about 600 pg per milliliter (2200 pmol per liter) at the time of ovulation. They may rise to nearly 20,000 pg per milliliter (70,000 pmol per liter) during pregnancy. After menopause, serum estradiol concentrations fall to values similar to or lower than those in men of similar age (5 to 20 pg per milliliter [18 to 74 pmol per liter]) (Yen, S. S. C. and Jaffe, R. B. eds. Reproductive Endocrinology: Physiology, Pathophysiology and Clinical Management, 3rd ed. Philadelphia: W. B. Saunders, 1991).
Breast cancer is a hormone-dependent disease. Women without functioning ovaries who never receive estrogen replacement do not develop breast cancer. The female-to-male ratio for the disease is about 150 to 1. A host of findings indicate that hormones play a critical role as promoters of the disease. For most epithelial malignancies, a log-log plot of incidence versus age shows a straight-line increase with every year of life. A similar plot for breast cancer shows the same straight-line increase, but with a decrease in slope beginning at the age of menopause. The three dates in a woman""s life that have a major impact on breast cancer incidence are age of menarche, age at first full-term pregnancy, and age of menopause. Women who experience menarche at age 16 have only 50 to 60 percent of the lifetime breast cancer risk of women who experience menarche at age 12. Similarly, menopause occurring 10 years before the median age (52 years), whether natural or surgically induced, reduces lifetime breast cancer risk by about 35 percent. Compared with nulliparous women, women who have a first full-term pregnancy by age 18 have 30 to 40 percent the risk of breast cancer. Thus, length of menstrual lifexe2x80x94particularly the fraction occurring before the first full-term pregnancyxe2x80x94is a substantial component of the total risk of breast cancer. This factor can account for 70 to 80 percent of the variation in breast cancer frequency in different countries.
International variation has provided some of the most important clues on hormonal carcinogenesis. A woman living to age 80 in North America has 1 chance in 9 of developing invasive breast cancer. Asian women have one-fifth to one-tenth the risk of breast cancer of women in North America or Western Europe. Asian women have substantially lower concentrations of estrogens and progesterone. These differences cannot be explained on a genetic basis, because Asian women living in a Western environment have a risk identical to that of their Western counterparts. These women also differ markedly in height and weight from Asian women in Asia; height and weight are critical regulators of age of menarche and have substantial effects on plasma concentrations of estrogens. (Lippman, M. E., Breast Cancer, Chapter 91, in Harrison""s Principles of Internal Medicine, 14th ed., 1998). Thus despite the beneficial effects which estrogens play in maintaining health, the administration of estrogens may also cause adverse effects on a subject""s health such as an increased risk of breast cancer breast cancer.
Menopause occurs naturally at an average age of 50 to 51 years in the USA. As ovaries age, response to pituitary gonadotropins (follicle-stimulating hormone [FSH] and luteinizing hormone [LH]) decreases, initially resulting in shorter follicular phases (thus, shorter menstrual cycles), fewer ovulations, decreased progesterone production, and more irregularity in cycles. Eventually, the follicle fails to respond and does not produce estrogen. The transitional phase, during which a woman passes out of the reproductive stage, begins before menopause. It is termed the climacteric or perimenopause, although many persons refer to it as menopause.
Premature menopause refers to ovarian failure of unknown cause that occurs before age 40. It may be associated with smoking, living at high altitude, or poor nutritional status. Artificial menopause may result from oophorectomy, chemotherapy, radiation of the pelvis, or any process that impairs ovarian blood supply.
The compositions and methods of the present invention act to promote bone formation, lower blood cholesterol and treat hyperlipidemia. These effects are accomplished by the compositions and methods of the invention with a substantial reduction of the concomitant liability of adverse effects associated with estrogen administration. Not being bound by any single theory, it is believed that administration of the estrogen agonist/antagonist of the invention results in a bone loss preventing effect and a lipid lowering effect distinct from that of statins. The combined overall effect of combined treatment with estrogen agonists/antagonists and statins is a beneficial one and is substantially free of the adverse effects attributed to estrogen administration.